引入clippy，并根据clippy的提示，修改部分代码 (#575)

kernel/crates/bitmap/src/lib.rs

@@ -2,6 +2,7 @@
 #![feature(core_intrinsics)]
 #![allow(incomplete_features)] // for const generics
 #![feature(generic_const_exprs)]
+#![allow(clippy::needless_return)]
 
 #[macro_use]
 extern crate alloc;

kernel/crates/crc/src/lib.rs

@@ -2,6 +2,8 @@
 #![feature(const_for)]
 #![feature(const_mut_refs)]
 #![feature(const_trait_impl)]
+#![allow(clippy::needless_return)]
+
 #[cfg(test)]
 extern crate std;
 

kernel/crates/kdepends/src/lib.rs

@@ -1,7 +1,5 @@
 #![no_std]
 
-#[allow(unused)]
-#[macro_use]
 pub extern crate thingbuf;
 
 pub extern crate memoffset;

kernel/crates/klog_types/src/lib.rs

@@ -1,6 +1,7 @@
 #![no_std]
 #![feature(const_refs_to_cell)]
 #![feature(const_size_of_val)]
+#![allow(clippy::needless_return)]
 
 extern crate alloc;
 use core::{fmt::Debug, mem::size_of_val};
@@ -88,7 +89,7 @@ impl AllocatorLog {
 
     /// 当前日志是否有效
     pub fn is_valid(&self) -> bool {
-        if self.validate_checksum() == false {
+        if !self.validate_checksum() {
             return false;
         }
 
@@ -102,7 +103,7 @@ impl AllocatorLog {
 
 impl PartialOrd for AllocatorLog {
     fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
-        return self.id.partial_cmp(&other.id);
+        Some(self.cmp(other))
     }
 }
 

kernel/crates/system_error/src/lib.rs

@@ -1,4 +1,6 @@
 #![no_std]
+#![allow(clippy::needless_return)]
+#![allow(clippy::upper_case_acronyms)]
 
 use num_derive::{FromPrimitive, ToPrimitive};
 

kernel/crates/unified-init/src/lib.rs

@@ -1,4 +1,5 @@
 #![no_std]
+#![allow(clippy::needless_return)]
 
 use system_error::SystemError;
 pub use unified_init_macros as macros;